Secondary battery and method for manufacturing the same

ABSTRACT

Disclosed are a secondary battery and a method for manufacturing the same. According to an embodiment of the present invention, there is provided a secondary battery, including: an exterior material which includes a pouch film and a sealing portion formed at an outer side of the pouch film; and an electrode assembly which includes a plurality of electrode bodies laminated with a separator interposed therebetween and are packaged by the exterior material, wherein a pair of forming portions are formed within the pouch film to house the electrode assembly, and a predetermined interval is formed between the pair of forming portions.

This application is a continuation of U.S. patent application Ser. No.14/196,703 filed on Jun. 19, 2016, which claims priority from Koreanpatent application 10-2015-0091847 filed Jun. 29, 2015 with the KoreanIntellectual Property Office the disclosures of which are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a secondary battery and a method formanufacturing the same in embodiments thereof.

2. Description of the Related Art

Recently, a lithium secondary battery, which is rechargeable andlightweight and has a high energy and power density, has been widelyused as an energy source for wireless mobile devices. Further, as asolution to the problems such as air pollution and the greenhouse houseeffect which are caused by existing internal combustion engine vehiclesusing fossil fuels such as a gasoline vehicle and a diesel vehicle, ahybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV),a battery electric vehicle (BEV), an electric vehicle (EV), or the likehave been proposed. The lithium secondary battery may serve as a powersource for the alternative vehicles.

The lithium secondary battery is classified into a lithium ion batteryusing a liquid electrolyte and a lithium polymer battery using a polymerelectrolyte in terms of a type of electrolytic solutions. The lithiumsecondary battery is also classified into cylindrical, prismatic, and apouch shapes in terms of a shape of an exterior material in which anelectrode assembly is housed.

Among these, the pouch type lithium secondary battery is made of a metallayer (foil) and a pouch film which is formed of multi-layered syntheticresin layers and coated on upper and lower surfaces of the metal layer,the weight of the pouch type lithium secondary battery may be remarkablylighter than that of the cylindrical lithium secondary battery or theprismatic lithium secondary battery using a metallic can. Thus, thepouch type lithium secondary battery may be lightweight and may beamenable to a change in shape.

FIG. 1 is a development view of a conventional pouch shape secondarybattery 10 which is disclosed in Korean Patent Laid-Open Publication No.10-2013-0089614 (2013 Aug. 12), and FIG. 2 is a cross-sectional view ofthe pouch shape secondary battery 10 of FIG. 1.

Referring to FIGS. 1 and 2, the pouch shape secondary battery 10 isformed by packaging an electrode assembly 1, to which an electrode tab 2is attached, with an exterior material 3. The exterior material 3includes a sealing portion 4 and a pair of pouch films 5. Each of thepair of pouch films 5 includes a forming portion 6 to house theelectrode assembly 1. When a middle portion of the exterior material 3is folded, upper and lower parts of the electrode assembly 1 are housedin the pair of forming portions 6.

The forming portion 6 is formed by pressing an inside of the pouch film5 with a press or the like to allow the pouch film 5 to have apredetermined depth. In this regard, the depth at which the formingportion 6 may be formed about 7 mm at maximum, and therefore a thicknessof the electrode assembly 1 housed in the forming portion 6 has also adepth limitation (about 14 mm). Therefore, a capacity of the secondarybattery 10 has a limitation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a secondary battery anda method for manufacturing the same capable of increasing a thickness ofa secondary battery cell in embodiments thereof.

Another object of the present invention is to provide a high-capacitysecondary battery and a method for manufacturing the same by solving alimitation in a thickness of a secondary battery cell in embodimentsthereof.

In addition, another object of the present invention is to provide asecondary battery and a method for manufacturing the same capable ofactually increasing an energy density within the same volume by reducinga sealing side face in embodiments thereof.

According to one embodiment of the present invention, there is provideda secondary battery, including: an exterior material which includes apouch film and a sealing portion formed at an outer side of the pouchfilm; and an electrode assembly which includes a plurality of electrodebodies stacked with a separator interposed therebetween and are packagedby the exterior material, wherein a pair of forming portions are formedwithin the pouch film to house the electrode assembly, and apredetermined interval is formed between the pair of forming portions.

The pair of forming portions may face each other with the electrodeassembly interposed therebetween.

Each of the pair of forming portions may have a predetermined depth, anda thickness of the electrode assembly may have a relationship betweenthe predetermined interval and a predetermined depth represented byEquation 1 below:t≤T+2f  [Equation 1]

Here, t denotes the thickness of the electrode assembly, T denotes thepredetermined interval between the pair of forming portions, and fdenotes the predetermined depths of each of the pair of formingportions.

The predetermined interval may be a range of exceeding from 0 mm but 20mm or less.

Lateral intervals between the pair of forming portions and outermostparts of the pouch film may be a half (½) or more of the predeterminedinterval.

Both sides of the electrode assembly may be respectively provided withelectrode tabs connected through a welding portion, and longitudinalintervals between the pair of forming portions and outermost parts ofthe pouch film may be a sum or more of the half (½) of the predeterminedinterval and a width of the welding part.

According to another embodiment of the present invention, there isprovided a method for manufacturing a secondary battery, including:forming a pair of forming portions within a pouch film of an exteriormaterial which includes the pouch film and a sealing portion formed atan outer side of the pouch film; housing an electrode assembly whichincludes a plurality of electrode bodies stacked with a separatorinterposed therebetween and packaged by the exterior material within thepair of forming portions; and sealing the sealing portions positioned atboth sides with the electrode assembly interposed therebetween.

A predetermined interval may be formed between the pair of formingportions.

Each of the pair of forming portions may have a predetermined depth, anda thickness of the electrode assembly may have a relationship betweenthe predetermined interval and a predetermined depth represented byEquation 1 below:t≤T+2f  [Equation 1]

Here, t denotes the thickness of the electrode assembly, T denotes thepredetermined interval between the pair of forming portions, and fdenotes the predetermined depths of each of the pair of formingportions.

The predetermined interval may be a range of exceeding from 0 mm but 20mm or less.

Lateral intervals between the pair of forming portions and outermostparts of the pouch film may be a half (½) or more of the predeterminedinterval.

Both sides of the electrode assembly may be respectively provided withelectrode tabs connected through a welding portion, and longitudinalintervals between the pair of forming portions and outermost parts ofthe pouch film may be a sum or more of the half (½) of the predeterminedinterval and a width of the welding part.

According to the embodiments of the present invention, it is possible toincrease the thickness of the secondary battery cell by forming the pairof forming portions within one pouch film and forming a predeterminedinterval between the pair of forming portions.

According to the embodiments of the present invention, it is possible tomanufacture the high-capacity secondary battery by solving thelimitation in the thickness of the secondary battery cell.

Further, according to the embodiment of the present invention, it ispossible to actually increase the energy density within the same volumeby reducing the sealing side face.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a development view of a conventional pouch type secondarybattery;

FIG. 2 is a cross-sectional view of the pouch type secondary battery ofFIG. 1;

FIG. 3 is a development view of a secondary battery according to anembodiment of the present invention;

FIG. 4 is a cross-sectional view of a secondary battery according to anembodiment of the present invention; and

FIG. 5 is a perspective view of a secondary battery according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, specific embodiments of the present invention will bedescribed with reference to the accompanying drawings. But, these areonly an example, and the present invention is not limited thereto.

In description of the present invention, detailed description of thepublicly known functions and configurations that are judged to be ableto make the purport of the present invention unnecessarily obscure areomitted. In addition, terms or words used in the specification andclaims should not be construed as limited to a lexical meaning, andshould be understood as appropriate notions by the inventor based onthat he/she is able to define terms to describe his/her invention in thebest way to be seen by others.

However, those skilled in the art will appreciate that such embodimentsare provided for illustrative purposes and do not limit subject mattersto be protected as disclosed in the detailed description and appendedclaims. Therefore, it will be apparent to those skilled in the art thatvarious alterations and modifications of the embodiments are possiblewithin the scope and spirit of the present invention and duly includedwithin the range as formed by the appended claims.

FIG. 3 is a development view of a secondary battery 100 according to anembodiment of the present invention.

Referring to FIG. 3, the secondary battery 100 includes an electrodeassembly 110 including a plurality of electrode bodies which are stackedand a separator interposed between the plurality of electrode bodies. Topackage the electrode assembly 110, an exterior material 130 including apouch film 150 and a sealing portion 140 formed on an outercircumference of the pouch film 150 may be used.

The secondary battery 100 may be a pouch type secondary battery. Theelectrode assembly 110 may be a jelly roll in an oval shape or the likein which cathode plates and anode plates are alternately stacked witheach other with the separator interposed therebetween. Both ends of theelectrode assembly 110 have electrode tabs 120, and welding portions 125may be formed between the electrode tab 120 and the electrode assembly110 to connect these parts with each other.

The pouch film 150 may include aluminum. The reason of using thealuminum in the pouch film 150 is to resist severe thermal environments,mechanical impacts, or the like as well as to achieve miniaturization,weight reduction, and slimness.

The pouch film 150 includes a pair of forming portions 160 for housingthe electrode assembly 110. The forming portion 160 may be in a recessedshape, and may be formed by pressing the inside of the pouch film 150 orthe like.

However, when the forming portion 160 is pressed too hard, the pouchfilm 150 may be damaged, and therefore the depth of the forming portion160 is limited. As a result, in the conventional secondary battery, thethickness of the electrode assembly 110 housed in the forming portion160 is also limited due to the limitation in the depth of the formingportion 160.

According to the embodiments of the present invention, the pair offorming portions 160 may be formed in the pouch film 150, and apredetermined interval T may be formed between the pair of formingportions 160. Further, the secondary battery may be formed by placingone side of the electrode assembly 110 within one forming portion 160,and then wrapping the other side of the electrode assembly 110 with theother forming portion 160. An extra space is additionally generated asmuch as the predetermined interval T formed between the pair of formingportions 160, and thus the thickness of a space, in which the electrodeassembly 110 is received, may be increased as much as the predeterminedinterval T.

Herein, the pair of forming portions 160 may face each other and theelectrode assembly 110 is interposed therebetween. Further, thepredetermined interval may be in a range between 0 mm, exclusive, and 20mm, inclusive.

As illustrated in FIG. 3, a lateral distance between each of the pair offorming portions 160 and the sealing portion 140 may a half (½) or moreof the predetermined interval T. When the pouch film 150 is wrapped, thepair of forming portions 160 and both sides of the outermost part of thepouch film 150 abut each other. Therefore, it is preferable that each ofthe lateral intervals is the half (½) or more of the predeterminedinterval T.

Further, a longitudinal distance between each of the forming portions160 and the outermost part of the pouch film 150 may be W+T/2 or more.Here, W is a width of the welding portion 125.

FIG. 4 is a cross-sectional view of the secondary battery 100 accordingto the embodiment of the present invention. Referring to FIG. 4, thesecondary battery 100 may be formed by packaging the electrode pouch 110with the exterior material 130 including the pouch film 150. Thesecondary battery 100 may be sealed with a sealing portion 140 formed atan outer side of the exterior material 130.

A thickness t of the electrode assembly 110 within the secondary battery100 may be represented by Equation 1 below:t≤T+2f  [Equation 1]

Here, f is a depth of each of the forming portions 160.

The above relationship Equation 1 may be expressed as illustrated inFIG. 4. Therefore, the thickness t of the electrode assembly 110 may bethicker than the conventional secondary battery, and it is possible tomanufacture the secondary battery 100 having a thickness of 14 mm ormore that may not be achieved in the related art.

Further, as illustrated in FIG. 4, only one of two long edges of thesecondary battery 100 may be sealed with the sealing portion 140.Therefore, the energy density within the same volume may be increased asmuch as the sealed surface is reduced.

FIG. 5 is a perspective view of the secondary battery 100 according tothe embodiment of the present invention.

Referring to FIG. 5, in the secondary battery 100 of the presentinvention, the thickness of the electrode assembly 110 is not limiteddue to a depth of the forming portion 160. The thickness of theelectrode assembly 110 may be formed thicker due to the interval presentbetween the forming portions 160. Thereby, the capacity of the secondarybattery 100 may be increased. Further, the energy density may beactually increased by reducing a sealing area of the secondary battery100.

Hereinafter, a method for manufacturing a secondary battery 100according to an embodiment of the present invention will be described.

First, the pouch film 150 and the exterior material 130 including thesealing portion 140 formed at the outer side of the pouch film 150 maybe prepared. The pair of forming portions 160 may be formed within thepouch film 150. The predetermined interval may be formed between thepair of forming portions 160 and the predetermined interval may be in arange between 0 mm, exclusive, and 20 mm, inclusive. Further, theinterval between each of the pair of forming portions 160 and thesealing portion 140 may a half (½) or more of the predeterminedinterval.

Next, the electrode assembly 110 may be housed within the pair offorming portions 160. In this case, the secondary battery may be formedby placing the electrode assembly 110 over one forming portion 160, andthen wrapping the electrode assembly 110 with the other forming portion160. Therefore, the extra space is additionally generated as much as thepredetermined interval T, which is a distance between the formingportions 160. Thus, the thickness of the electrode assembly 110 may beincreased as much as the predetermined interval T.

Further, the sealing portions 140 are attached to each other so that theelectrode assembly 110 is enclosed within the pouch film 150.

While the present invention has been described with reference to thepreferred embodiments, it will be understood by those skilled in therelated art that various modifications and variations may be madetherein without departing from the scope of the present invention asformed by the appended claims. Therefore, the scope of the presentinvention should not be formed by the described embodiment but should beformed by the appended claims and their equivalents.

DESCRIPTION OF REFERENCE NUMERALS

-   -   100: secondary battery    -   110: electrode assembly    -   120: electrode tab    -   125: welding portion    -   130: exterior material    -   140: sealing portion    -   150: pouch film    -   160: forming portion

What is claimed is:
 1. A secondary battery, comprising: an electrode assembly; an exterior material comprising a sealing portion, first and second forming portions for housing the electrode assembly, and an interval disposed between the first and second forming portions, the interval including a first boundary between the interval and the first forming portion and a second boundary between the interval and the second forming portion; and electrode tabs connected to the electrode assembly through welding portions; wherein the exterior material is folded using the first boundary and the second boundary such that the exterior material packages the electrode assembly by enclosing the electrode assembly to form three sealed sides and one non-sealed side, wherein a thickness of the electrode assembly is larger than a sum of a depth of the first forming portion and a depth of the second forming portion, and wherein at least one sealed side that does not face the non-sealed side is provided with the electrode tabs.
 2. The secondary battery of claim 1, wherein the interval does not include any folded area in an interior between the first boundary and the second boundary.
 3. The secondary battery of claim 2, wherein the welding portions are formed outside of the forming portions.
 4. The secondary battery of claim 2, wherein both sealed sides that do not face the non-sealed side are provided with the electrode tabs.
 5. The secondary battery of claim 2, wherein lateral intervals between the first and second forming portions and the sealing portion are a half (½) or more of a predetermined interval.
 6. The secondary battery of claim 2, wherein longitudinal intervals between the first and second forming portions and the sealing portion are a sum or more of the half (½) of a predetermined interval and a width of the welding portion.
 7. The secondary battery of claim 2, wherein the non-sealed side has a seamless sidewall.
 8. The secondary battery of claim 2, wherein a length of the interval is substantially the same as that of a predetermined interval.
 9. The secondary battery of claim 8, wherein the depths of the first forming portion and the second forming portion are equal.
 10. The secondary battery of claim 2, wherein the thickness of the electrode assembly is larger than the length of the first and second forming portions at the non-sealed side.
 11. A secondary battery, comprising: an electrode assembly; an exterior material comprising a pair of forming portions for housing the electrode assembly, a sealing portion and an interval between the pair of forming portions; and electrode tabs connected to the electrode assembly through welding portions; wherein the exterior material packages the electrode assembly by enclosing the electrode assembly to form three sealed sides and one non-sealed side, wherein the pair of forming portions face each other in a thickness direction such that the exterior material is folded around the electrode assembly using the non-sealed side, wherein the interval includes a first boundary and a second boundary facing each other, wherein the external material is folded using the first and second boundaries and the interval is devoid of any folded area in an interior between the first boundary and the second boundary, wherein a thickness of the electrode assembly is larger than a sum of the depths of the pair of forming portions, and wherein the welding portions are formed outside of the forming portions.
 12. The secondary battery of claim 11, wherein both sealed sides that do not face the non-sealed side are provided with the electrode tabs.
 13. The secondary battery of claim 11, wherein lateral intervals between the pair of forming portions and the sealing portion are a half (½) or more of a predetermined interval.
 14. The secondary battery of claim 11, wherein longitudinal intervals between the pair of forming portions and the sealing portion are a sum or more of the half (½) of a predetermined interval and a width of the welding portion.
 15. The secondary battery of claim 11, wherein the non-sealed side has a seamless sidewall.
 16. The secondary battery of claim 11, wherein the thickness of the electrode assembly is larger than the length of the pair of forming portions at the non-sealed side.
 17. The secondary battery of claim 11, wherein a length of the interval is substantially the same as that of a predetermined interval. 